U.S. patent number 10,690,810 [Application Number 15/739,586] was granted by the patent office on 2020-06-23 for antireflection film and display device having hard coating layer with specified surface roughness and internal haze.
This patent grant is currently assigned to LG CHEM LTD.. The grantee listed for this patent is LG CHEM, LTD.. Invention is credited to Yeong Rae Chang, Kyung Ki Hong, Min Soo Kim, Tae Soon Kim, Jae Pil Koo, Hye Min Lee, Soo Kyoung Lee, Joo Jong Moon, Jin Young Park, Jung Hyun Seo, Jae Hoon Shim.
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United States Patent |
10,690,810 |
Chang , et al. |
June 23, 2020 |
Antireflection film and display device having hard coating layer
with specified surface roughness and internal haze
Abstract
The present invention relates to an antireflection film
comprising a hard coating layer in which a ten-point average
roughness (Rz) of the surface irregularities is 0.05 .mu.m to 0.2
.mu.m and an internal haze is 0.5% to 5%; and a low refractive
index layer formed on the hard coating layer, and a display device
comprising the antireflection film.
Inventors: |
Chang; Yeong Rae (Daejeon,
KR), Shim; Jae Hoon (Daejeon, KR), Seo;
Jung Hyun (Daejeon, KR), Park; Jin Young
(Daejeon, KR), Lee; Soo Kyoung (Daejeon,
KR), Koo; Jae Pil (Daejeon, KR), Kim; Tae
Soon (Daejeon, KR), Kim; Min Soo (Daejeon,
KR), Hong; Kyung Ki (Daejeon, KR), Moon;
Joo Jong (Daejeon, KR), Lee; Hye Min (Daejeon,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG CHEM LTD. (Seoul,
KR)
|
Family
ID: |
58502585 |
Appl.
No.: |
15/739,586 |
Filed: |
September 12, 2016 |
PCT
Filed: |
September 12, 2016 |
PCT No.: |
PCT/KR2016/010272 |
371(c)(1),(2),(4) Date: |
December 22, 2017 |
PCT
Pub. No.: |
WO2017/043948 |
PCT
Pub. Date: |
March 16, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180313978 A1 |
Nov 1, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Sep 11, 2015 [KR] |
|
|
10-2015-0129309 |
Sep 9, 2016 [KR] |
|
|
10-2016-0116740 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08F
222/10 (20130101); G02B 1/14 (20150115); C09D
4/00 (20130101); G02B 1/11 (20130101); C09D
133/04 (20130101); C09D 133/08 (20130101); G02F
1/133502 (20130101); G02F 2201/38 (20130101); C08G
77/045 (20130101) |
Current International
Class: |
C09D
133/08 (20060101); G02B 1/11 (20150101); G02F
1/1335 (20060101); C09D 4/00 (20060101); C09D
133/04 (20060101); C08F 222/10 (20060101); G02B
1/14 (20150101); C08G 77/04 (20060101) |
Field of
Search: |
;252/582,587
;264/1.24,1.7,1.9
;359/359,360,361,488.01,580,584,585,586,588,589,590,592,593,594,597,599,601,609,614,615
;427/162,163.1,163.2,164,165 ;428/1.5,1.6 |
References Cited
[Referenced By]
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|
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|
Primary Examiner: Dunning; Ryan S
Attorney, Agent or Firm: Dentons US LLP
Claims
The invention claimed is:
1. An antireflection film, comprising: a hard coating layer having
a ten-point average roughness (Rz) of the surface irregularities in
range of 0.05 .mu.m to 0.2 .mu.m and an internal haze in range of
2.1% to 5%; a low refractive index layer formed on the hard coating
layer; and wherein in the result of the diffuse distribution of the
reflected light source for the antireflection film, the average
value of the ratio of the respective light intensity values to the
specular reflection light intensity values at an angle of
+1.degree. and -1.degree. from the specular reflection is 0.005 to
0.100, wherein the result of the diffuse distribution of the
reflected light source for the antireflection film applies an
incident angle of 45.degree., and the specular reflection light
intensity value is a reflection diffuse light intensity value at
45.degree. corresponding to the specular reflection of the incident
angle.
2. The antireflection film of claim 1, wherein the hard coating
layer has an internal haze in a range of 2.1% to 2.7%.
3. The antireflection film of claim 1, wherein the antireflection
film has a reflectivity of 1.6% or less in a wavelength region of
380 nm to 780 nm.
4. The antireflection film of claim 1, wherein the hard coating
layer comprises a binder resin including a (co)polymer of a
photopolymerizable compound and an organic or inorganic fine
particle dispersed in the binder resin.
5. The antireflection film of claim 4, wherein the hard coating
layer comprises at least two types of organic or inorganic fine
particles, and the difference in the refractive index between at
least two types in the at least two types of organic or inorganic
fine particles is 0.01 to 0.08.
6. The antireflection film of claim 4, wherein the hard coating
layer further comprises an inorganic nanoparticle having a diameter
of 1 nm to 150 nm.
7. The antireflection film of claim 4, wherein the binder resin of
the hard coating layer further comprises a high molecular weight
(co)polymer having a weight average molecular weight of 10,000 or
higher.
8. The antireflection film of claim 1, wherein the low refractive
index layer comprises a binder resin comprising a (co)polymer of a
photopolymerizable compound and a fluorine-containing compound or a
silicon-based compound containing a photoreactive functional
group.
9. The antireflection film of claim 8, wherein the binder resin of
the low refractive index layer comprises polysilsesquioxane in
which at least one reactive functional group is substituted.
10. The antireflection film of claim 9, wherein the at least one
reactive functional group is selected from the group consisting of
an alcohol, an amine, a carboxylic acid, an epoxide, an imide, a
(meth)acrylate, a nitrile, a norbornene, an olefin, a polyethylene
glycol, a thiol, and a vinyl group.
11. The antireflection film of claim 1, wherein the photoreactive
functional group contained in the fluorine-containing compound or
silicon-based compound is at least one functional group selected
from the group consisting of a (meth)acrylate group, epoxide group,
vinyl group, and thiol group.
12. The antireflection film of claim 1, wherein the
fluorine-containing compound containing a photoreactive functional
group includes at least one selected from the group consisting of
i) an aliphatic compound or an aliphatic cyclic compound in which
at least one photoreactive functional group is substituted and at
least one fluorine is substituted on at least one carbon; ii) a
heteroaliphatic compound or a heteroaliphatic cyclic compound in
which at least one photoreactive functional group is substituted,
at least one hydrogen is substituted with fluorine, and at least
one carbon is substituted with silicon; iii) a
polydialkylsiloxane-based polymer in which at least one
photoreactive functional group is substituted and at least one
fluorine is substituted on at least one silicon; and iv) a
polyether compound in which at least one photoreactive functional
group is substituted and at least one hydrogen is substituted with
fluorine.
13. The antireflection film of claim 1, further comprising an
inorganic fine particle dispersed in the binder resin.
14. The antireflection film of claim 13, wherein the inorganic fine
particles included in the low refractive index layer include at
least one selected from the group consisting of hollow inorganic
fine particles having a number average particle diameter of 10 to
200 nm and solid-type inorganic fine particles having a number
average particle diameter of 0.5 to 10 nm.
15. The antireflection film of claim 13, wherein the low refractive
index layer comprises 10 to 400 parts by weight of the inorganic
fine particles and 20 to 300 parts by weight of the
fluorine-containing compound or silicon-based compound including a
photoreactive functional group based on 100 parts by weight of the
(co)polymer of the photopolymerizable compound.
16. The antireflection film of claim 1, wherein the low refractive
index layer comprises 0.5 to 40 parts by weight of the
polysilsesquioxane in which at least one reactive functional group
is substituted, based on 100 parts by weight of the (co)polymer of
the photopolymerizable compound.
17. A display device comprising the antireflection film of claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application is a National Stage Entry of International
Application No. PCT/KR2016/010272, filed on Sep. 12, 2016, and
claims the benefit of and priority to Korean Application No.
10-2015-0129309, filed on Sep. 11, 2015, and Korean Application No.
10-2016-0116740, filed on Sep. 9, 2016, all of which are hereby
incorporated by reference in their entirety for all purposes as if
fully set forth herein.
TECHNICAL FIELD
The present invention relates to an antireflection film and a
display device. More specifically, the present invention relates to
an antireflection film having reduced sparkling phenomenon and
excellent visibility when applied to a high-resolution display and
having excellent workability during the production of a display,
and a display device providing optical characteristics such as
excellent external black visibility and contrast ratio, etc., and
high screen sharpness.
BACKGROUND ART
In general, a flat panel display device such as a PDP or a LCD is
equipped with an antireflection film for minimizing the reflection
of light incident from the outside.
As a method for minimizing the reflection of light, there exist a
method (anti-glare: AG coating) in which a filler such as an
inorganic fine particle is dispersed in a resin and coated on a
substrate film to impart irregularities; a method (anti-reflection:
AR coating) of using the interference of light by forming a
plurality of layers having different refractive indexes on a
substrate film; or a method for mixing them, etc.
Among them, in the case of the AG coating, the absolute amount of
the reflected light is equivalent to that of a general hard
coating, but a low reflection effect can be obtained by reducing
the amount of light entering the eye using light scattering through
irregularities. However, since the AG coating has poor surface
sharpness due to the surface irregularities, many studies on AR
coating have been conducted recently.
As for a film using the AR coating, a multi-layer structure in
which a hard coating layer (high refractive index layer), a low
reflective coating layer, and the like are stacked on a substrate
film has been commercialized. However, in the case of a clear
coating having no irregularities on the surface, there are
disadvantages in that the anti-glare effect is not sufficient and a
defect inside the display is easily visible.
Accordingly, many studies have been actively conducted to minimize
the reflection of light incident from the outside while maintaining
the sharpness of the image. However, as the resolution of the
display increases, the degree of improvement of the physical
properties is insufficient. Recently, there are cases in which a
COT (color filter on TFT) structure is used as a liquid crystal
panel of a liquid crystal display device.
When a liquid crystal panel having such a COT structure is used,
the reflectivity of the inside of the panel is increased due to the
metals included in the electrodes and the like, and thus the
optical characteristics of the display such as external black
visibility and contrast ratio are reduced. Accordingly, there is a
need to develop a surface coating film having an excellent
antireflection function while increasing the yield of the display
panel.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
It is an object of the present invention to provide an
antireflection film having reduced sparkling phenomenon and
excellent visibility when applied to a high-resolution display and
having excellent workability during the production of a
display.
Further, it is another object of the present invention to provide a
display device providing optical characteristics such as excellent
external black visibility and contrast ratio, etc., and high screen
sharpness.
Technical Solution
In the present disclosure, there is provided an antireflection film
including a hard coating layer in which a ten-point average
roughness (Rz) of the surface irregularities is 0.05 .mu.m to 0.2
.mu.m and an internal haze is 0.5% to 5%; and a low refractive
index layer formed on the hard coating layer.
The ten-point average roughness (Rz) of the surface irregularities
of the hard coating layer is a measurement result using a
non-contact surface shape measuring instrument (3D optical
profiler).
In the result of the diffuse distribution of the reflected light
source for the antireflection film, the average value of the ratio
of the respective light intensity values to the specular reflection
light intensity values at an angle of +1.degree. and -1.degree.
from the specular reflection may be 0.005 to 0.100 or 0.010 to
0.080.
The result of the diffuse distribution of the reflected light
source for the antireflection film applies an incident angle of
45.degree., and the specular reflection light intensity value is a
diffuse reflection light intensity value at 45.degree.
corresponding to the specular reflection of the incident angle.
The antireflection film may have a reflectivity of 1.6% or less in
a wavelength region of 380 nm to 780 nm.
The hard coating layer may include a binder resin including a
(co)polymer of a photopolymerizable compound and an organic or
inorganic fine particle dispersed in the binder resin.
The organic or inorganic fine particles may be spherical particles
having a particle diameter of 0.5 to 10 .mu.m or 0.5 to 5 .mu.m,
preferably 1 to 5 .mu.m, more preferably 1 to 3 .mu.m.
Further, the hard coating layer may include at least two types of
organic or inorganic fine particles, and the difference in the
refractive index between at least two types in the at least two
types of organic or inorganic fine particles may be 0.01 to
0.08.
The hard coating layer may include 1 to 20 parts by weight of the
organic or inorganic fine particles based on 100 parts by weight of
the (co)polymer of the photopolymerizable compound.
The binder resin of the hard coating layer may further include a
high molecular weight (co)polymer having a weight average molecular
weight of 10,000 or higher.
The hard coating layer may further include an inorganic
nanoparticle having a diameter of 1 nm to 150 nm or 5 nm to 120
nm.
The low refractive index layer may include a binder resin including
a (co)polymer of a photopolymerizable compound and a
fluorine-containing compound or a silicon-based compound containing
a photoreactive functional group.
The photopolymerizable compound may include a monomer or oligomer
containing a (meth) acrylate or vinyl group.
The photoreactive functional group contained in the
fluorine-containing compound or silicon-based compound may be at
least one selected from the group consisting of a (meth)acrylate
group, epoxide group, vinyl group, and thiol group.
The fluorine-containing compound containing a photoreactive
functional group may be at least one compound selected from the
group consisting of i) an aliphatic compound or an aliphatic cyclic
compound in which at least one photoreactive functional group is
substituted and at least one fluorine is substituted on at least
one carbon; ii) a heteroaliphatic compound or a heteroaliphatic
cyclic compound in which at least one photoreactive functional
group is substituted, at least one hydrogen is substituted with
fluorine, and at least one carbon is substituted with silicon; iii)
a polydialkylsiloxane-based polymer in which at least one
photoreactive functional group is substituted and at least one
fluorine is substituted on at least one silicon; and iv) a
polyether compound in which at least one photoreactive functional
group is substituted and at least one hydrogen is substituted with
fluorine.
The antireflection film may further include an inorganic fine
particle dispersed in the binder resin.
The inorganic fine particles included in the low refractive index
layer may include at least one selected from the group consisting
of hollow inorganic fine particles having a number average particle
diameter of 10 to 200 nm and solid-type inorganic fine particles
having a number average particle diameter of 0.5 to 10 nm.
The low refractive index layer may include 10 to 400 parts by
weight of the inorganic fine particles and 20 to 300 parts by
weight of the fluorine-containing compound or silicon-based
compound including a photoreactive functional group relative to 100
parts by weight of the (co)polymer of the photopolymerizable
compound.
The binder resin of the low refractive index layer may further
include polysilsesquioxane having at least one reactive functional
group substituted therein. The low refractive index layer may
include 0.5 to 40 parts by weight of the polysilsesquioxane having
at least one reactive functional group substituted therein based on
100 parts by weight of the (co)polymer of the photopolymerizable
compound.
Further, in the present disclosure, there may be provided a display
device including the antireflection film described above.
The display device may be a display device including a pair of
polarizing plates facing each other; a thin film transistor, a
color filter, and a liquid crystal cell sequentially stacked
between the pair of polarizing plates; and a backlight unit.
The antireflection film may be formed on the other surface of the
polarizing plate in contact with the liquid crystal cell, or
between the polarizing plate and backlight unit.
Advantageous Effects
According to the present invention, there may be provided an
antireflection film having reduced sparkling phenomenon and
excellent visibility when applied to a high-resolution display and
having excellent workability during the production of a display,
and a display device providing optical characteristics, such as
excellent external black visibility and contrast ratio, and high
screen sharpness.
The antireflection film is applied to a high-resolution display,
thereby providing a high hiding power of a panel defect and
excellent antireflection performance and visibility. In particular,
it may be applied to a COT panel having a high inner panel
reflectivity to express the antireflection performance.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 schematically shows a cross section of a liquid crystal
display device equipped with the antireflection film of Example
1.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Hereinafter, the antireflection film and display device according
to specific embodiments of the present invention will be described
in more detail.
In the present disclosure, a photopolymerizable compound
collectively refers to a compound which causes a polymerization
reaction when irradiated with a light, for example, when irradiated
with a visible light or ultraviolet light. Further, a
fluorine-containing compound refers to a compound containing at
least one fluorine element in the compound.
Further, a (meth)acryl may include both acryl and methacryl.
In addition, a (co)polymer may include both a co-polymer and a
homo-polymer.
Moreover, hollow silica particles refer to silica particles derived
from a silicon compound or an organosilicon compound, in which
voids are present on the surface and/or inside of the silica
particles.
According to one embodiment of the present invention, there may be
provided an antireflection film including a hard coating layer in
which a ten-point average roughness (Rz) of the surface
irregularities is 0.05 .mu.m to 0.2 .mu.m and an internal haze is
0.5% to 5%; and a low refractive index layer formed on the hard
coating layer.
In the past, a hard coating layer having fine irregularities was
usually referred to as an AG coating layer, and was composed of an
irregularity structure having a height of several hundred nm to
several .mu.m. The film on which an irregularity structure is
formed has excellent an anti-glare effect because it may induce a
diffuse reflection when a light enters from the outside, but an
image that comes out from the inside is distorted on the surface,
thereby causing a problem of decreasing the sharpness and
resolution of the image. In addition, a high-resolution display of
UHD (ultrahigh definition) or higher has a severe image distortion,
and thus, it is necessary to control the concavo-convex
structure.
Accordingly, the present inventors have derived an optimum surface
irregularity structure capable of simultaneously implementing the
antireflection effect and visibility. The surface roughness of the
antireflection film is represented by ten-point average roughness
(Rz) of the surface irregularities. The ten-point average roughness
refers to the difference in the average value between 5 peaks of
the maximum height and 5 peaks of the lowest valley within the
measurement length in a surface irregularities curve.
Herein, if the Rz, which is the height of the ten-point
irregularities, is between 0.05 .mu.m to 0.2 .mu.m, it is possible
to simultaneously implement the antireflection effect and
visibility. If the ten-point average roughness of the surface
irregularities of the hard coating layer is less than 0.05 .mu.m,
the antireflection effect and the hiding power of a panel defect
are reduced, and if the ten-point average roughness of the surface
irregularities of the hard coating layer exceeds 0.2 .mu.m, a
phenomenon of resolution deterioration such as sparkling may be
observed, and sharpness may be lowered.
The ten-point average roughness of the surface irregularities of
the hard coating layer may be measured by using a non-contact
surface shape measuring instrument (3D optical profiler).
In addition, in order to improve the hiding power of a panel defect
while maintaining the visibility of the antireflection film, it is
possible to impart haze to the antireflection film.
Specifically, if the internal haze of the antireflection film was
between 0.5% to 5%, it was possible to enhance the hiding power of
a panel defect while maintaining the sharpness. If the internal
haze of the antireflection film is less than 0.5%, the hiding power
of a panel may be decreased, and if the internal haze of the
antireflection film exceeds 5%, it may cause a decrease in the
visibility, such as a decrease in the contrast ratio.
In the result of the diffuse distribution of the reflected light
source for the antireflection film, the average value of the ratio
of the respective light intensity values to the specular reflection
light intensity values at an angle of +1.degree. and -1.degree.
from the specular reflection may be 0.005 or higher, 0.005 to 0.100
or 0.010 to 0.080.
In order to substantially grasp the hiding power of a display
device panel, it is possible to measure the diffuse light
distribution of the reflected light source. If the ratio of the
respective light intensity values to the specular reflection light
intensity values at an angle of +1.degree. and -1.degree. from
specular reflection in the result of the diffuse distribution of
the reflected light source for the antireflection film is 0.005 or
higher, the hiding power of the display device panel is favorable.
In contrast, if the ratio is less than 0.005, the ratio at which
the light is diffused is significantly lowered, and the hiding
power of the display device panel may also become poor.
Meanwhile, in the result of the diffuse distribution of the
reflected light source for the antireflection film, if the ratio of
the respective light intensity values to the specular reflection
light intensity values at an angle of +1.degree. and -1.degree.
from specular reflection becomes too high, for example, if it
exceeds 0.100, the image may appear distorted or the clarity of
colors may be deteriorated, which may be disadvantageous in
implementing a high-resolution display.
When an incident light is introduced into the optical film such as
the antireflection film, a diffuse specular reflection occurs in a
direction symmetrical to the normal line of the film, and a part of
light is diffused.
As a result, when incident light is introduced at a predetermined
angle, for example, at an angle of 30.degree. to 60.degree., or
45.degree. with respect to the normal direction of the film, the
diffusion distribution of the reflection light source indicated by
the antireflection film can be obtained by measuring within a
predetermined angle range with respect to the light which was made
incident, diffused and reflected, for example, in the range of
-85.degree. to 85.degree. with respect to the normal direction of
the surface of the antireflection film.
The diffuse light distribution can be measured by using a
photo-goniometer and a specific measuring equipment is not limited.
However, for example, the reflection diffuse strength can be
measured using .left brkt-top.GP-200.right brkt-bot. manufactured
by Murakami Color Research Laboratory.
The result of the diffuse distribution of the reflected light
source for the antireflection film applies an incident angle of
45.degree.. Further, the specular reflection light intensity value
is a diffusion reflection light intensity value at 45.degree.
corresponding to the specular reflection of the incident angle.
The specular reflection light intensity value may be 75 to 95 or 80
to 90. If the specular reflection light intensity value of the
antireflection film is 75 to 95, the color can be clearly
implemented, and a clear image without distortion on the interface
can be implemented. In contrast, if the light intensity value is
too small, the light scattering may increase and the clarity of the
image and color may be lowered. Further, if the light intensity
value is too large, the hiding power may be significantly lowered,
for example, the transparent electrode of the panel may become
visible.
As described above, the antireflection film including a low
refractive index layer formed on the hard coating layer in which a
ten-point average roughness (Rz) of the surface irregularities is
0.05 .mu.m to 0.2 .mu.m and an internal haze is 0.5% to 5%, may
have a reflectivity of 1.6% or less may exhibit an average
reflectivity in a wavelength region of 380 nm to 780 nm. Thus, the
antireflection film may maximize the antireflection function and
inhibit deterioration of visibility caused by an external light in
a COT panel, etc.
The ten-point average roughness (Rz) of the surface irregularities
and the internal haze of the hard coating layer can be controlled
by the composition of a composition for forming the hard coating
layer and by a method for forming a hard coating layer.
The hard coating layer may be formed from a hard coating
composition including a photopolymerizable compound, a
photoinitiator, and organic fine particles or inorganic fine
particles. Specifically, the hard coating layer may include a
binder resin including a (co)polymer of a photopolymerizable
compound and organic or inorganic fine particles dispersed in the
binder resin.
The photopolymerizable compound included in the hard coating
composition for forming a hard coating layer may be a
photopolymerizable/photocurable compound capable of causing a
polymerization reaction when irradiated with light such as
ultraviolet rays, and may be one that is conventional in the
relevant.
Specifically, the (co)polymer of the photopolymerizable compound
included in the hard coating layer may be a (co)polymer formed from
at least one selected from a reactive acrylate oligomer group
consisting of urethane acrylate oligomer, epoxide acrylate
oligomer, polyester acrylate, and polyether acrylate; and a
polyfunctional acrylate monomer group consisting of
dipentaerythritol hexaacrylate, dipentaerythritol hydroxy
pentaacrylate, pentaerythritol tetraacrylate, pentaerythritol
triacrylate, trimethylene propyl triacrylate, propoxylated glycerol
triacrylate, trimethylpropane ethoxy triacrylate, 1,6-hexanediol
diacrylate, propoxylated glycerol triacrylate, tripropylene glycol
diacrylate, and ethylene glycol diacrylate.
The hard coating layer includes organic or inorganic fine particles
together with the (co)polymer of the photopolymerizable compound to
impart surface irregularities and internal haze. The organic or
inorganic fine particles may be spherical particles having a
particle diameter of 0.5 to 10 .mu.m or 0.5 to 5 .mu.m, preferably
1 to 5 .mu.m, more preferably 1 to 3 .mu.m.
The particle diameter of the organic or inorganic fine particles
may be equal to or higher than 0.5 .mu.m in order to express the
surface irregularities and internal haze, and may be equal to or
lower than 10 .mu.m in terms of the haze or thickness of the
coatings. For example, For example, when the particle diameter of
the fine particle exceeds 10 .mu.m and becomes excessively large,
the thickness of the coating has to be increased in order to match
the fine surface irregularities, and thus there arises a problem
that the inner cracking property of the film may be reduced.
The organic or inorganic fine particles are not limited to specific
examples of the organic or inorganic fine particles. For example,
the organic or inorganic fine particles may be an acrylic resin, a
styrene resin, organic fine particles composed of an epoxide resin
and a nylon resin, silicon oxide, titanium dioxide, Indium oxide,
tin oxide, zirconium oxide, and zinc oxide.
Specific examples of the organic or inorganic fine particles are
not limited, but for example, the organic and inorganic fine
particles may be organic fine particles consisting of acryl-based
resin, styrene-based resin, epoxy resin, and nylon resin, or may be
inorganic fine particles consisting of silicon oxide, titanium
dioxide, indium oxide, tin oxide, zirconium oxide, and zinc
oxide.
The hard coating layer may include 1 to 20 parts by weight or 5 to
15 parts by weight, preferably 6 to 10 parts by weight of the
organic or inorganic fine particles relative to 100 parts by weight
of the (co)polymer of the photopolymerizable compound.
If the organic or inorganic fine particles are contained in an
amount of less than 1 part by weight based on 100 parts by weight
of the (co)polymer of the photopolymerizable compound, the haze
value caused by an internal scattering may not be sufficiently
implemented. Further, if the amount of the organic or inorganic
fine particles exceeds 20 parts by weight based on 100 parts by
weight of the (co)polymer of the photopolymerizable compound, the
viscosity of the coating composition is increased and thus a poor
coating property may be observed.
Furthermore, the refractive index of the organic or inorganic fine
particles is different from the refractive index of a photocurable
resin forming a matrix. An appropriate difference in refractive
index is determined according to the content of the particles, and
it is preferable to have the difference in refractive index of 0.01
to 0.08. If the difference in the refractive index between the fine
particles and the photocurable resin is less than 0.01, it may be
difficult to obtain an appropriate haze value. In addition, if the
difference in the refractive index between the fine particles and
the photocurable resin exceeds 0.08, a desired level of the surface
irregularities cannot be obtained because a very small amount of
the particles must be used.
Specifically, the organic and inorganic fine particles may be at
least one selected from an organic fine particle group consisting
of an acryl-based resin, styrene-based resin, epoxy resin, nylon
resin, and a copolymer resin thereof; and an inorganic fine
particle group consisting of silicon oxide, titanium dioxide,
indium oxide, tin oxide, zirconium oxide, and zinc oxide.
More specifically, the organic fine particles may be at least one
selected from the group consisting of methyl (meth)acrylate, ethyl
(meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate,
isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl
(meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate,
stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, polyethylene
glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate,
glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate,
diethylaminoethyl (meth)acrylate, styrene, p-methylstyrene,
m-methylstyrene, p-ethylstyrene, m-ethylstyrene, p-chlorostyrene,
m-chlorostyrene, p-chloromethylstyrene, m-chloromethylstyrene,
styrenesulfonic acid, p-t-butoxystyrene, m-t-butoxystyrene, vinyl
acetate, vinyl propionate, vinyl butyrate, vinyl ether, allyl butyl
ether, allyl glycidyl ether, (meth)acrylic acid, maleic acid,
unsaturated carboxylic acid, alkyl (meth)acrylamide,
(meth)acrylonitrile, and (meth)acrylate.
Further, as the organic fine particles, one single substance
selected from the group consisting of polystyrene, polymethyl
methacrylate, polymethyl acrylate, polyacrylate,
polyacrylate-co-styrene, polymethyl acrylate-co-styrene, polymethyl
methacrylate-co-styrene, polycarbonate, polyvinyl chloride,
polybutylene terephthalate, polyethylene terephthalate, polyamides,
polyimides, polysulfone, polyphenylene oxide, polyacetal, epoxy
resin, phenol resin, silicone resin, melamine resin,
benzoguanamine, polydivinylbenzene, polydivinylbenzene-co-styrene,
polydivinylbenzene-co-acrylate, polydiallyl phthalate, and triallyl
isocyanurate polymer, or a copolymer of two or more thereof may be
used, but is not limited thereto.
Meanwhile, the hard coating layer may further include an inorganic
nanoparticle having a diameter of 1 nm to 50 nm or 5 nm to 120 nm.
A predetermined functional group or compound may be bonded to the
surface of the inorganic nanoparticle.
As the inorganic nanoparticles are used, it is possible to smoothly
control the shape of surface irregularities of the hard coating
layer and improve the mechanical characteristics of the coating
layer. Herein, the inorganic nanoparticles may be used in an amount
of 10 parts by weight or less based on 100 parts by weight of the
(co)polymer of the photopolymerizable compound. Specific examples
of the inorganic nanoparticles include silicon oxide, alumina,
titania, etc.
The hard coating composition for forming a hard coating layer may
include a photoinitiator, and as the photoinitiator, any
photoinitiators conventionally known in the art may be used without
particular limitation. Examples of the photoinitiator include one
single substance or a mixture of two or more selected from
1-hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal,
hydroxydimethyl acetophenone, benzoin, benzoin methyl ether,
benzoin ethyl ether, benzoin isopropyl ether, and benzoin butyl
ether, but the present invention is not limited by the examples
described above.
Herein, the photoinitiator may be added in an amount of 0.1 to 10
parts by weight based on 100 parts by weight of the
photopolymerizable compound. If the photoinitiator is contained in
an amount of less than 0.1 part by weight based on 100 parts by
weight of the photopolymerizable compound, a sufficient photocuring
due to an ultraviolet irradiation may not occur. If the
photoinitiator is contained in an amount of exceeding 10 parts by
weight based on 100 parts by weight of the photopolymerizable
compound, the film strength of the finally formed anti-glare film
may be lowered.
Meanwhile, the hard coating composition for forming a hard coating
layer may further include an organic solvent. When such an organic
solvent is added, there is no limitation in its composition.
However, in consideration of securing an appropriate viscosity of
the coating composition and the film strength of the finally formed
film, the organic solvent may be used in an amount of preferably 50
to 500 parts by weight, more preferably 100 to 400 parts by weight,
and most preferably 150 to 350 parts by weight based on 100 parts
by weight of the photocurable resin.
Herein, the type of the organic solvent that can be used is not
limited in its constitution, but one type or a mixture of one or
more types selected from the group consisting of lower alcohols
having 1 to 6 carbon atoms, acetates, ketones, cellosolves,
dimethylformamide, tetrahydrofuran, propylene glycol monomethyl
ether, and xylene may be used.
Herein, examples of the lower alcohols include methanol, ethanol,
isopropyl alcohol, butyl alcohol, isobutyl alcohol, diacetone
alcohol or the like, but the present invention is not limited
thereto. Further, as the acetates, methyl acetate, ethyl acetate,
isopropyl acetate, butyl acetate, or cellosolve acetate may be
used, and as the ketones, methyl ethyl ketone, methyl isobutyl
ketone, acetylacetone, or acetone may be used, but are not limited
to the examples described above.
Meanwhile, the hard coating composition for forming a hard coating
layer may further include at least one additive selected from the
group consisting of a leveling agent, a wetting agent, and a
defoaming agent. Herein, the additives may each be added within the
range of 0.01 to 10 parts by weight based on 100 parts by weight of
the photopolymerizable compound.
The leveling agent serves to uniformize the surface of a coated
coating film using an anti-glare coating composition. Further, as
the wetting agent serves to lower the surface energy of the
anti-glare coating composition, it helps to achieve a uniform
coating when coating the anti-glare coating composition on a
transparent substrate layer.
Herein, the defoaming agent may be added to remove bubbles in the
anti-glare coating composition.
The hard coating layer may have a thickness of from 0.5 .mu.m to
100 .mu.m.
Meanwhile, the low refractive index layer can be prepared using a
photocurable coating composition including a photopolymerizable
compound, a fluorine-containing compound or silicon-based compound
containing a photoreactive functional group, and a photoinitiator.
The antireflection film including such a low refractive index layer
can improve abrasion resistance or scratch resistance while further
lowering reflectivity and increasing light transmittance, and at
the same time, it can secure an excellent antifouling property
against external pollutants.
Specifically, the low refractive index layer may include a binder
resin including a (co)polymer of a photopolymerizable compound and
a fluorine-containing compound or silicon-based compound containing
a photoreactive functional group.
The photopolymerizable compound may include a monomer or an
oligomer containing a (meth)acrylate or vinyl group. Specifically,
the photopolymerizable compound may include a monomer or an
oligomer containing one or more or two or more, or three or more of
(meth)acrylates or vinyl groups.
Specific examples of the monomer or oligomer containing
(meth)acrylate include, pentaerythritol tri(meth)acrylate,
pentaerythritol tetra(meth)acrylate, dipentaerythritol
penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,
tripentaerythritol hepta(meth)acrylate, trilene diisocyanate,
xylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane
tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate,
trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate,
butanediol dimethacrylate, hexaethyl methacrylate, butyl
methacrylate, or a mixture of two or more thereof, or
urethane-modified acrylate oligomer, epoxide acrylate oligomer,
ether acrylate oligomer, dendritic acrylate oligomer, or a mixture
of two or more thereof. Herein, the molecular weight of the
oligomers is preferably 1,000 to 10,000.
Specific examples of the monomer or oligomer containing a vinyl
group include divinylbenzene, styrene, or para-methyl styrene.
Meanwhile, the photopolymerizable compound may further include a
fluorine-based (meth)acrylate-based compound in addition to the
monomers or oligomers described above. When the fluorine-based
(meth)acrylate-based compound is further included, the weight ratio
of the fluorine-based (meth)acrylate-based compound to the monomer
or oligomer containing a (meth)acrylate or vinyl group may be 0.1%
to 10%.
Specific examples of the fluorine-based (meth)acrylate-based
compound include at least one compound selected from the group
consisting of the following Chemical Formulae 1 to 5.
##STR00001##
in Chemical Formula 1, R.sup.1 is a hydrogen group, or an alkyl
group having 1 to 6 carbon atoms, a is an integer of 0 to 7, and b
is an integer of 1 to 3.
##STR00002##
in Chemical Formula 2, c is an integer of 1 to 10.
##STR00003##
in Chemical Formula 3, d is an integer of 1 to 11.
##STR00004##
in Chemical Formula 4, e is an integer of 1 to 5.
##STR00005##
in Chemical Formula 5, f is an integer of 4 to 10.
On the other hand, the fluorine-containing compound or
silicon-based compound containing a photoreactive functional group
may include or be substituted with at least one photoreactive
functional group, and the photoreactive functional group refers to
a functional group which can participate in a polymerization
reaction by irradiation of light, for example, by irradiation of
visible light or ultraviolet light. The photoreactive functional
group may include various functional groups known to be able to
participate in a polymerization reaction by irradiation of light.
Specific examples thereof include a (meth)acrylate group, an
epoxide group, a vinyl group or a thiol group.
The fluorine-containing compound or silicon-based compound
containing a photoreactive functional group may each have a
weight-average molecular weight (weight-average molecular weight in
terms of polystyrene measured by GPC method) of 2,000 to 200,000,
preferably 5,000 to 100,000.
If the weight-average molecular weight of the fluorine-containing
compound or silicon-based compound containing a photoreactive
functional group is too small, the fluorine-containing compounds or
silicon-based compounds in the photocurable coating composition
cannot be uniformly and effectively aligned on the surface and are
positioned inside of the finally produced low refractive index
layer. Accordingly, the antifouling property of the surface of the
low refractive index layer is reduced, and the crosslinking density
of the low refractive index layer is lowered, thereby deteriorating
the mechanical properties, such as the overall strength and scratch
resistance.
Further, if the weight-average molecular weight of the
fluorine-containing compound or silicon-based compound containing a
photoreactive functional group is too large, the compatibility with
other components in the photocurable coating composition may be
lowered, and thus the haze of the finally produced low refractive
index layer may increase or the light transmittance may decrease,
and the strength of the low refractive index layer may also be
lowered.
Specifically, the fluorine-containing compound containing a
photoreactive functional group may be i) an aliphatic compound or
an aliphatic cyclic compound in which at least one photoreactive
functional group is substituted and at least one fluorine is
substituted on at least one carbon; ii) a heteroaliphatic compound
or a heteroaliphatic cyclic compound in which at least one
photoreactive functional group is substituted, at least one
hydrogen is substituted with fluorine, and at least one carbon is
substituted with silicon; iii) a polydialkylsiloxane-based polymer
(for example, polydimethylsiloxane-based polymer) in which at least
one photoreactive functional group is substituted and at least one
fluorine is substituted on at least one silicon; iv) a polyether
compound in which at least one photoreactive functional group is
substituted and at least one hydrogen is substituted with fluorine;
or a mixture of two or more of i) to iv), or a copolymer
thereof.
The photocurable coating composition may include 20 to 300 parts by
weight of the fluorine-containing compound or silicon-based
compound based on 100 parts by weight of the photopolymerizable
compound.
The fluorine-containing compound containing a photoreactive
functional group may further include silicon or a silicon compound.
That is, the fluorine-containing compound containing a
photoreactive functional group may optionally contain silicon or a
silicon compound therein, and specifically, the content of silicon
in the fluorine-containing compound containing a photoreactive
functional group may be 0.1% by weight to 20% by weight.
The antireflection film may further include inorganic fine
particles dispersed in the binder resin.
More specifically, the inorganic fine particles included in the low
refractive index layer may include at least one selected from the
group consisting of hollow inorganic fine particles having a number
average particle diameter of 10 to 200 nm and solid-type inorganic
fine particles having a number average particle diameter of 0.5 to
10 nm.
The solid-type inorganic fine particles refer to particles having a
maximum diameter in a micron or nano unit and having no void
therein. Specific examples of the solid-type inorganic fine
particles include nanosilica particles.
Further, the hollow inorganic fine particles refer to particles
having a maximum diameter in a micron or nano unit and having voids
on the surface and/or inside thereof. Specific examples of the
hollow inorganic fine particles include hollow silica
particles.
The hollow silica particles refer to silica particles derived from
a silicon compound or an organosilicon compound, in which voids are
present on the surface and/or inside of the silica particles.
In the hollow silica particles, inorganic fine particles may have a
number average particle diameter of 10 to 100 nm. The hollow silica
particles refer to silica particles in which voids are present on
the surface and/or inside of the particles. The hollow silica
particles may have a refraction index than lower than that of the
particles filled therein and thus can exhibit excellent
antireflection properties.
The hollow silica particles may have a number average particle
diameter of 10 to 100 nm, preferably 20 to 70 nm, more preferably
30 to 70 nm; and the shape of the particles is preferably
spherical, but it may be amorphous.
In addition, as the hollow silica particles, a hollow silica
particle whose surface is coated with a fluorine-based compound may
be used either alone or in combination with hollow silica particles
whose surface is not coated with a fluorine-based compound. When
the surface of the hollow silica particles is coated with a
fluorine-based compound, the surface energy may be further reduced.
Accordingly, the hollow silica particles may be more uniformly
distributed in the photocurable coating composition of the
embodiment above, and the durability and scratch resistance of the
film obtained from the photocurable coating composition may be
further improved.
As a method of coating the surface of the hollow silica particles
with a fluorine-based compound, a conventionally known particle
coating method, polymerization method, and the like may be used
without particular limitation. For example, the fluorine-based
compound may be bonded to the surface of the hollow silica
particles via hydrolysis and a condensation reaction by subjecting
the hollow silica particles and the fluorine-based compound to a
sol-gel reaction in the presence of water and a catalyst.
Further, the hollow silica particles may be included in the
composition in a colloidal phase dispersed in a predetermined
dispersion medium. The colloidal phase containing the hollow silica
particles may contain an organic solvent as a dispersion
medium.
Herein, the hollow silica may include a predetermined functional
group substituted on the surface thereof to be more readily
dispersed in the organic solvent. Examples of organic functional
groups which can be substituted on the surface of the hollow silica
particles are not particularly limited, but for example, a (meth)
acrylate group, a vinyl group, a hydroxyl group, an amine group, an
allyl group, an epoxy group, a hydroxyl group, an isocyanate group,
an amine group, or fluorine, etc. may be substituted on the surface
of the hollow silica.
The solid content of the hollow silica particles in the colloidal
phase of the hollow silica particles may be determined in
consideration of the range of content of the hollow silica in the
photocurable coating composition of the one embodiment or the
viscosity of the photocurable coating composition, etc., and for
example, the solid content of the hollow silica particles in the
colloidal phase may range from 5% by weight to 60% by weight.
Herein, examples of the organic solvent in the dispersion medium
include alcohols such as methanol, isopropyl alcohol, ethylene
glycol and butanol, etc.; ketones such as methyl ethyl ketone and
methyl isobutyl ketone, etc.; aromatic hydrocarbons such as toluene
and xylene, etc.; amides such as dimethylformamide,
dimethylacetamide and N-methylpyrrolidone; etc.; esters such as
ethyl acetate, butyl acetate and gamma-butylolactone, etc; ethers
such as tetrahydrofuran and 1,4-dioxane, etc.; or a mixture
thereof.
The low refractive index layer may include 10 to 400 parts by
weight or 50 to 300 parts by weight of the inorganic fine particles
based on 100 parts by weight of the (co)polymer of the
photopolymerizable compound. If the inorganic fine particles are
added in an excessive amount, the scratch resistance and abrasion
resistance of the coating film may be deteriorated due to a
decrease in the content of the binder.
Meanwhile, the binder resin of the low refractive index layer may
further include polysilsesquioxane in which at least one reactive
functional group is substituted. As the polysilsesquioxane in which
at least one reactive functional group is substituted contains
reactive functional groups on the surface thereof, the mechanical
properties of the low refractive index layer, for example, scratch
resistance, may be enhanced.
The low refractive index layer may include 0.5 to 40 parts by
weight or 1.5 to 30 parts by weight of the polysilsesquioxane
having at least one reactive functional group substituted therein
relative to 100 parts by weight of the (co)polymer of the
photopolymerizable compound.
If the content of the polysilsesquioxane having at least one
reactive functional group substituted therein relative to the
(co)polymer of the photopolymerizable compound in the photocurable
coating composition is too small, it may be difficult to ensure
sufficient scratch resistance of the coating film or the binder
resin formed upon photocuring of the photocurable coating
composition. Further, if the content of the polysilsesquioxane
having at least one reactive functional group substituted therein
relative to the photopolymerizable compound in the photocurable
coating composition is too large, the transparency of the low
refractive index layer or antireflection film manufactured from the
photocurable coating composition may be decreased, and the scratch
resistance may rather be decreased.
The reactive functional group substituted in the polysilsesquioxane
may include at least one functional group selected from the group
consisting of alcohol, amine, carboxylic acid, epoxide, imide,
(meth)acrylate, nitrile, norbornene, olefin [ally, cycloalkenyl, or
vinyldimethylsilyl, etc.], polyethylene glycol, thiol, and vinyl
and may preferably be epoxide or (meth)acrylate.
More specific examples of the reactive functional group include
(meth)acrylates, alkyl (meth)acrylates having 1 to 20 carbon atoms,
cycloalkyl epoxide having 3 to 20 carbon atoms, and cycloalkane
epoxide having 1 to 10 carbon atoms.
The alkyl (meth)acrylate means that the other part of `alkyl` that
is not bonded to (meth)acrylate is a boding position, the
cycloalkyl epoxide means that the other part of `cycloalkyl` that
is not bonded to an epoxide is a bonding position, and the alkyl
cycloalkane epoxide means that the other part of `alkyl` that is
not bonded to a cycloalkane epoxide is a bonding position.
Meanwhile, the polysilsesquioxane in which at least one reactive
functional group is substituted may further include at least one
unreactive functional group selected from the group consisting of a
linear or branched alkyl group having 1 to 20 carbon atoms, a
cyclohexyl group having 6 to 20 carbon atoms, and an aryl group
having 6 to 20 carbon atoms, in addition to the reactive functional
groups described above. Thus, as the reactive functional groups and
unreactive functional groups are substituted on the surface of the
polysilsesquioxane, the siloxane bond (--Si--O--) in the
polysilsesquioxane in which at least one reactive functional group
is substituted is positioned inside the molecule and is not exposed
to the outside, so that the compatibility with other components can
be further enhanced. Further, as the siloxane bonds are firmly
bonded between the reactive functional groups or other organic
components, thereby being not separated by the external pressure.
Further, it can serve as a rigid support in the coating film or the
binder resin formed during the photocuring of the photocurable
coating composition. Therefore, the strength and scratch resistance
of the finally produced low reflective index layer and
antireflection film can be greatly increased.
Meanwhile, the polysilsesquioxane may be represented by
(RSiO.sub.1.5).sub.n (where n is 4 to 30 or 8 to 20), and may have
various structures such as random, ladder type, cage and partial
cage, etc.
However, in order to enhance the physical properties and quality of
the low refractive index layer and antireflection film produced
from the photocurable coating composition, a polyhedral oligomeric
silsesquioxane having a cage structure, in which at least one
reactive functional group is substituted, may be used as the
polysilsesquioxane in which at least one reactive group is
substituted. Further, more preferably, the polyhedral oligomeric
silsesquioxane having a cage structure, in which at least one
functional group is substituted, may include 8 to 20 silicon atoms
in a molecule.
Furthermore, at least one silicon atom of the polyhedral oligomeric
silsesquioxane having a cage structure may be substituted with a
reactive functional group, and the silicon atoms in which no
reactive functional groups are substituted may be substituted with
the unreactive functional groups described above.
As at least one silicon atom of the polyhedral oligomeric
silsesquioxane having a cage structure is substituted with a
reactive functional group, the mechanical properties of the coating
film or the binder resin formed upon photocuring of the
photocurable coating composition may be enhanced. In addition, as
the remaining silicon atoms are substituted with unreactive
functional groups, a steric hindrance appears molecular
structurally, which significantly decreases the frequency or
probability of exposure of the siloxane bond (--Si--O--) to the
outside, thereby enhancing the compatibility with other organic
components, and the siloxane bonds are firmly bonded between the
reactive functional groups or other organic components, thereby
being not separated by the external pressure. Further, it can serve
as a rigid support in the coating film or the binder resin formed
during the photocuring of the photocurable coating composition.
Therefore, the strength and scratch resistance of the finally
produced low refractive index layer or antireflection film can be
greatly increased.
Examples of the polyhedral oligomeric silsesquioxane (POSS) having
a cage structure in which at least one reactive functional group is
substituted include POSS in which at least one alcohol is
substituted, such as TMP diolisobutyl POSS, cyclohexanediol
isobutyl POSS, 1,2-Propanediolisobutyl POSS, octa(3-hydroxy-3
methylbutyldimethylsiloxy) POSS, etc.; POSS in which at least one
amine is substituted, such as aminopropylisobutyl POSS,
aminopropylisooctyl POSS, aminoethylaminopropyl isobutyl POSS,
N-phenylaminopropyl POSS, N-methylaminopropyl isobutyl POSS,
octaammonium POSS, aminophenylcyclohexyl POSS, aminophenylisobutyl
POSS, etc.; POSS in which at least one carboxylic acid is
substituted, such as maleamic acid-cyclohexyl POSS, maleamic
acid-isobutyl POSS, octa maleamic acid POSS, etc; POSS in which at
least one epoxide is substituted, such as epoxycyclohexylisobutyl
POSS, epoxycyclohexyl POSS, glycidyl POSS, glycidylethyl POSS,
glycidylisobutyl POSS, glycidylisooctyl POSS, etc.; POSS in which
at least one imide is substituted, such as POSS maleimide
cyclohexyl, POSS maleimide isobutyl, etc.; POSS in which at least
one (meth)acrylate is substituted, such as ccrylolsobutyl POSS,
(meth)acrylisobutyl POSS, (meth)acrylate cyclohexyl POSS,
(meth)acrylate isobutyl POSS, (meth)acrylate ethyl POSS,
(meth)acrylethyl POSS, (meth)acrylate isooctyl POSS,
(meth)acryllsooctyl POSS, (meth)acrylPhenyl POSS, (meth)acryl POSS,
acrylo POSS, etc.; POSS in which at least one nitrile group is
substituted, such as cyanopropylisobutyl POSS, etc.; POSS in which
at least one norbornene is substituted, such as
norbornenylethylethyl POSS, norbornenylethylisobutyl POSS,
norbornenylethyl disilanoisobutyl POSS, trisnorbornenyl isobutyl
POSS, etc.; POSS in which at least one vinyl group is substituted,
such as allylisobutyl POSS, monovinylisobutyl POSS,
octacyclohexenyldimethylsilyl POSS, octavinyldimethylsilyl POSS,
octavinyl POSS, etc.; POSS in which at least one olefin is
substituted, such as allylisobutyl POSS, monovinylisobutyl POSS,
octacyclohexenyldimethylsilyl POSS, octavinyldimethylsilyl POSS,
octavinyl POSS, etc.; POSS in which a PEG having 5 to 30 carbon
atoms is substituted; or POSS in which at least one thiol group is
substituted, such as mercaptopropylisobutyl POSS or
Mercaptopropyllsooctyl POSS, etc.
Any compound known to be usable in the photocurable resin
composition may be used as the photopolymerization initiator
without particular limitation. Specifically, a benzophenone-based
compound, an acetophenone-based compound, a nonimidazole-based
compound, a triazine-based compound, an oxime-based compound, or a
mixture of two or more thereof may be used.
The photopolymerization initiator may be used in an amount of 1 to
100 parts by weight based on 100 parts by weight of the
photopolymerizable compound. If the amount of the
photopolymerization initiator is too small, the photocurable
coating composition may be uncured in the photocuring step and thus
residual substances may appear. If the amount of the
photopolymerization initiator is too large, the unreacted initiator
may remain as an impurity or the crosslinking density may be
reduced, which in turn may deteriorate the mechanical properties of
the manufactured film or significantly increase the
reflectivity.
Meanwhile, the photocurable coating composition may further include
an organic solvent.
Non-limiting examples of the organic solvent include ketones,
alcohols, acetates and ethers, or mixtures of two or more
thereof.
Specific examples of the organic solvent include ketones such as
methyl ethyl ketone, methyl isobutyl ketone, acetylacetone or
isobutyl ketone, etc.; alcohols such as methanol, ethanol,
n-propanol, i-propanol, n-butanol, i-butanol or t-butanol, etc.;
acetates such as ethyl acetate, i-propyl acetate, or polyethylene
glycol monomethyl ether acetate, etc.; ethers such as
tetrahydrofuran or propylene glycol monomethyl ether, etc.; or a
mixture of two or more thereof.
The organic solvent may be added at the time of mixing the
respective components to be included in the photocurable coating
composition, or may be included in the photocurable coating
composition as the respective components are added in a state of
being dispersed or mixed in the organic solvent.
If the content of the organic solvent in the photocurable coating
composition is too small, the flowability of the photocurable
coating composition may be reduced, resulting in defects, such as
generation of stripes in the finally produced film, or the like.
Further, if the organic solvent is added in an excessive amount,
the solid content is lowered, and the coating and film formation
are not sufficiently made, so that the physical properties or the
surface characteristics of the film may be reduced, and defects may
occur during the drying and curing processes. Accordingly, the
photocurable coating composition may include the organic solvent
such that the concentration of the total solid content of the
components contained therein may be 1% by weight to 50% by weight
or 2% by weight to 20% by weight
Meanwhile, the antireflection film may be obtained by coating the
hard coating composition onto one side of a substrate, and drying
and photocuring the same, followed by coating a coating composition
for forming a low refractive index layer on the formed hard coating
layer and then photocuring the coated product. Herein, the hard
coating layer may be semi-cured, and a method of performing a final
curing when curing the low refractive index layer is most
preferable.
The specific type and thickness of the substrate are not
particularly limited, and any substrate known to be usable in the
production of a low refractive index layer or antireflection film
may be used without particular limitation.
A method and apparatus conventionally used for coating the
photocurable coating composition may be used without particular
limitation, and for example, a bar coating method such as Meyer
bar, a gravure coating method, a 2-roll reverse coating method, a
vacuum slot die coating method, and 2 roll coating method, etc. may
be used.
The hard coating layer may preferably have a final dry thickness of
1 .mu.m to 10 .mu.m, and if the final dry thickness is 1 .mu.m or
less, the mechanical strength of the coating layer is lowered and
it may be difficult to implement fine irregularities on the
surface. Further, it the final dry thickness is 10 .mu.m or higher,
there may be a disadvantage in that cracks may easily occur when
handling the coating film, because the coating layer is thick. The
low refractive index layer may have a thickness of 1 nm to 300 nm
or 50 nm to 200 nm.
In the step of photocuring the photocurable coating composition,
ultraviolet rays or visible rays having a wavelength of 200 to 400
nm may be irradiated, and an exposure amount during irradiation may
preferably be 100 to 4,000 mJ/cm.sup.2. The exposure time is not
particularly limited, and may be appropriately adjusted depending
on the exposure apparatus used, the wavelength of the irradiation
light, or the exposure amount.
Further, in the step of photocuring the photocurable coating
composition, nitrogen purging or the like may be performed in order
to apply nitrogen atmosphere conditions.
The antireflection film produced by the above-described method may
have an average reflectivity of 1.6% or less.
Meanwhile, according to another embodiment of the present
invention, there may be provided a display device including the
above-described antireflection film.
The display device may be a display device including a pair of
polarizing plates facing each other; a thin film transistor, a
color filter, and a liquid crystal cell sequentially stacked
between the pair of polarizing plates; and a backlight unit.
As shown in FIG. 1, the schematic structure of the display device,
according to FIG. 1, is equipped with a liquid crystal panel having
a structure in which a thin film transistor, a color filter, and a
liquid crystal cell are sequentially stacked, and polarizing plates
equipped on both sides thereof.
The antireflection film may be formed on the other surface of the
polarizing plate in contact with the liquid crystal cell, or
between the polarizing plate and backlight unit.
Specific embodiments of the present invention will be described in
more detail by way of Examples. However, the Examples are only for
illustrative of the specific embodiments of the invention, and the
disclosure of the specific embodiments of the invention is not
intended to be limited by these Examples.
Preparation Examples 1 to 5: Preparation of Hard Coating
Solutions
Anti-glare hard coating compositions were prepared by mixing the
components in Table 1 below.
[Component Information] BEAMSET 371: Manufactured by Arakawa, epoxy
acrylate polymer, molecular weight of 40,000 UA-306I:
Urethane-based acrylic oligomer (manufactured by Kyoeisha) 8BR-500:
Photocurable urethane acrylate polymer (MW 250,000, manufactured by
Dae Sung Chemical Co., Ltd.) TMPTA: Trimethylolpropane triacrylate
PETA: Pentaerythritol triacrylate (Polyfunctional monomer,
molecular weight of 298) Irgacure 184: Photoinitiator (manufactured
by Ciba) IPA: Isopropyl alcohol EtOH: Ethanol 103BQ: Spherical
acrylic-styrene copolymer resin particles (average particle
diameter of about 2 .mu.m, refractive index of about 1.515,
XX-103BQ, manufactured by Sekisui Plastic) 113BQ: Spherical
acrylic-styrene copolymer resin particles (average particle
diameter of about 2 .mu.m, refractive index of about 1.555,
XX-113BQ, manufactured by Sekisui Plastic) Spherical organic
particle 1: acrylic-styrene copolymer resin which is spherical
organic particle having an average particle diameter of 3.5 .mu.m
and a refractive index of 1.555 (XX-68BQ, manufactured by Sekisui
Plastic) X24-9600A: Silica particles having a volume average
particle diameter of 100 nm (manufactured by Shinetsu) MA-ST: Nano
silica dispersion (manufactured by Nissan Chemical)
TABLE-US-00001 TABLE 1 [(unit: g)] Preparation Preparation
Preparation Preparation Preparation Example 1 Example 2 Example 3
Example 4 Example 5 Acryl-based UA-306I 3 3 4 resin/oligomer
BEAMSET 371 8 8 8BR-500 8 6 6 Polyfunctional TMPTA 22 21 21 monomer
PETA 22 18 Photoinitiator Irgacure 184 2 2 2 2 2 Leveling agent BYK
300 0.5 0.5 0.5 0.5 0.5 Solvent IPA 33 33 40 4 66 EtOH 33 33 20 20
Fine particles 103BQ 0.5 113BQ 0.4 1 0.8 Spherical 1 organic
particles 1 X24-9600A 0.5 0.4 MA-ST 0.2 0.2 0.2 0.2 0.1 Total 99.2
99.6 93.7 57.9 87.6 Solid content (wt %) 33.82 33.59 35.82 58.30
38.28 Fine particle content (wt %) 0.56 0.96 1.06 1.26 1.03 Fine
particle/binder 1.87 3.2 3.53 4.2 3.43
Comparative Preparation Examples 1 to 4: Preparation of Hard
Coating Solutions
Anti-glare hard coating compositions were prepared in the same
manner as in Preparation Example 1, except that the components
shown in Table 2 were used.
TABLE-US-00002 TABLE 2 (unit: g) Comparative Comparative
Comparative Comparative Preparation Preparation Preparation
Preparation Example 1 Example 2 Example 3 Example 4 Acryl-based
UA-306I 3 4 resin/oligomer BEAMSET 371 4 4 8BR-500 5 Polyfunctional
TMPTA 22 26 10 monomer PETA 22 20 Photoinitiator Irgacure 184 2 2 2
2 Leveling agent BYK 300 0.5 0.5 0.5 0.5 Solvent IPA 33 66 66 33
EtOH 33 33 Fine particles 103BQ 0.2 0.5 113BQ 0.8 1 Spherical
organic particles 1 X24-9600A MA-ST 0.1 1.0 0.1 0.2 Total 99.4
100.5 98.8 99.7 Solid content (wt %) 33.53 33.63 32.93 33.16 Fine
particle content (wt %) 0.83 1.30 0.23 1.06 Fine particle/binder
2.77 4.33 0.7 3.53
Preparation Examples 6 and 7: Preparation of Resin Compositions for
Preparing Low Refractive Index Layer
Preparation Example 6: Preparation of Resin Composition for
Preparing Low Refractive Index Layer 1 (LR1)
0.37 g of a polyfunctional monomer (DPHA, molecular weight of 536),
0.13 g of a fluorine-based additive (RS907, DIC Corporation), 15 g
of methyl isobutyl ketone as a solvent and 16 g of propylene glycol
monomethyl ether were added and stirred. Then, 0.03 g of
polysilsesquioxane (MA0701, Hybrid Plastics Inc.) was added while
stirring, and 2.5 g of hollow silica (Thrulya 4320, manufactured by
Japan Catalysts and Chemicals) was added at last, and the mixture
was sufficiently stirred to prepare a low refractive index coating
solution.
Preparation Example 7: Preparation of Resin Composition for
Preparing Low Refractive Index Layer 2 (LR2)
0.37 g of a polyfunctional monomer (DPHA, molecular weight of 536),
0.13 g of a fluorine-based additive (RS907, DIC Corporation), 15 g
of methyl isobutyl ketone as a solvent and 16 g of propylene glycol
monomethyl ether were added and stirred. Then, 0.02 g of silica
dispersion (MIBK-ST, Nissan Chemical Industries, Ltd) having a
volume average particle diameter of 12 nm was added while stirring,
and 2.5 g of hollow silica (Thrulya 4320, Japan Catalysts and
Chemicals) was added at last, and the mixture was sufficiently
stirred to prepare a low refractive index coating solution.
Examples and Comparative Examples: Preparation of Antireflection
Films
The hard coating solutions prepared in each of the Preparation
Examples or Comparative Examples were coated onto a triacetyl
cellulose film having a thickness of 40 .mu.m with Meyer Bar, dried
at 90.degree. C. for 1 minute, and then irradiated with ultraviolet
rays at 150 mJ/cm.sup.2 to prepare an anti-glare coating film.
Thereafter, the resin compositions for preparing a low refractive
index layer prepared in each of Preparation Examples were coated on
the AG-coated surface with Meyer Bar #3 and dried at 90.degree. C.
for 1 minute.
The thus-dried product was irradiated with ultraviolet rays of 180
mJ/cm.sup.2 under nitrogen purging to prepare a low refractive
index layer having a thickness of 110 nm, thereby producing an
anti-glare/anti-reflection film.
Experimental Example: Measurement of Physical Properties of
Antireflection Films
The following experiments were conducted for the antireflection
films obtained in the Examples and Comparative Examples.
1. Measurement of Internal Haze
The surface of the antireflective film was subjected to
hydrophilization by corona treatment or the like, and then coated
with the hard coating solution to which no particles were
introduced in the Preparation Example 4, dried at 90.degree. C. for
1 minute, and irradiated with ultraviolet rays of 180 mJ/cm.sup.2
to perform a curing treatment. At the time of measuring haze, the
transmittance was measured according to JIS K 7361 standard and the
haze was measured according to JIS K 7105 standard. The average
value was calculated by measuring three times with a haze meter
(HM-150, A light source, Murakami Color Research Laboratory).
2. Measurement of Surface Roughness
The ten-point average roughness of the surface irregularities was
measured using a white light three-dimensional optical interference
profile (3D optical profiler, Model: NewView 7300, Zygo
Corporation). The measurement conditions are as follows: Lens
magnification: 10.times. (Mirau lens) Zoom magnification:
0.5.times. Measurement area (FoV): 1.40*1.05 mm.sup.2 Scan length:
5 .lamda.m bipolar Camera Mode: 640*480 Noise suppressing level
(Min Mod): 7% Number of analysis per measurement position: 1 FDA
Resolution: High 2G mode Correction method: Cylinder Fitting
The analysis was carried out by attaching a double-sided tape to
the opposite surface of the antireflection film to be measured and
placing it flat on a sample stage and then obtaining an optical
profiler image. Herein, the ten-point average roughness was
calculated by carrying out the measurement by setting the width to
3 mm and obtaining 2 or 3 line profiles from the obtained
image.
3. Measurement of Average Reflectivity
The average reflectivity was measured using SolidSpec 3700,
manufactured by SHIMADZU Corp.
Specifically, a black tape (3M) was attached to a surface of the
substrate film on which no hard coating layer was formed so that
light could not pass through it, and the measurement conditions
were fixed at a sampling interval of 1 nm, a time constant of 0.1
sec, a slit width of 20 nm and a medium scanning speed. Then, 100 T
mode was applied, and a light in a wavelength range of 380 nm to
780 nm was irradiated at room temperature to measure the
reflectivity.
4. Measurement of Image Clarity
The value of image clarity was measured using ICM-IT manufactured
by Suga Test Instrument Co., Ltd. Specifically, the substrate film
was mounted on a sample holder, and the image clarity was measured
when the slits were at 0.125 mm and 0.25 mm in a transmission
mode.
5. Measurement of Gloss
200/60.degree. gloss was measured using micro-TRI-gloss
manufactured by BYK Gardner. Specifically, a black tape (3M) was
attached to a surface of the substrate film on which no hard
coating layer was formed so that light could not pass through it,
and the incident angle of light was defined as an average value of
data each measured at least five times at 20.degree. and
60.degree..
6. Evaluation of Hiding Power
To evaluate the hiding power of a panel defect, the reflection
diffuse light intensity of the antireflection film was measured
using .left brkt-top.GP-200 .right brkt-bot. manufactured by
Murakami Color Research Laboratory.
The measurement conditions are as follows: Measurement mode:
reflection Angle of incidence: 45.degree. Measurement range:
-85.degree. to 85.degree. Light source aperture (VS1) set value: 1
(diameter of 3.5 mm) Receiver aperture (VS3) set value: 1 (diameter
of 2.3 mm)
The measurement was carried out in the order that a standard sample
was measured, the specular reflection light intensity was set to
100, and then the films of Examples and Comparative Examples were
measured. The standard sample is a film coated with the hard
coating having no particles on the same film as the substrate used
in Examples and Comparative Examples in a thickness of 5 to 10
.mu.m and satisfies a haze value of 0.1 or less.
A black tape (3M) was attached to a side opposite to the coated
surface of the film so that light could not pass through it, the
sample was mounted on the sample position, and then the reflection
diffuse light intensity was measured. At this time, if the specular
light intensity value is greater than 100, the sensitivity control
dial was controlled so that the specular light intensity value is
100. Thereafter, a black tape (3M) was attached to the surface of
the sample film to be measured on which no hard coating layer was
formed so that light could not pass through it, the sample was
placed on the sample position, and then the reflection diffusion
light intensity was measured in the measurement range of
-85.degree. to 85.degree.. The specular reflection light intensity
is a reflection diffuse light intensity value at 45.degree.
corresponding to the specular reflection of the incident angle. The
value of hiding power was obtained by dividing the respective light
intensities by the specular light intensities at +1.degree. to
-1.degree. from the specular reflection into calculate the ratios
thereof, and the average value was obtained.
TABLE-US-00003 TABLE 3 Details of the antireflection films of
Examples and experimental results thereof Example 1 Example 2
Example 3 Example 4 Example 5 Example 6 AG coating Preparation
Preparation Preparation Preparation Preparation Pre- paration
solution Example 1 Example 2 Example 3 Example 4 Example 5 Example
6 AG dry 6 7 6 6 7 6 thickness (.mu.m) LR coating Preparation
Preparation Preparation Preparation Preparation Pre- paration
solution Example 6 Example 6 Example 6 Example 6 Example 6 Example
7 Total Haze (%) 0.8 2.6 2.3 2.5 2.8 2.8 Internal 0.6 2.4 2.1 2.3
2.7 2.3 Haze (%) Rz(.mu.m) 0.1762 0.1936 0.1746 0.1932 0.167 0.1826
Average 1.1 1.1 1.1 1.1 1.1 1.1 reflectivity (%) Gloss 28/53.4
27/53.0 27/53 26.4/55 26/53.5 27/55 (20.degree./60.degree.) Image
clarity 67.7 58.7 57.9 59.4 68.3 59.8 0.125 mm slit Image clarity
71.3 60.3 59.2 60.4 72 61 0.25 mm slit Specular 85.5 60.3 59.2 60.4
54.94 85.16 reflection light intensity Hiding power 0.014 0.041
0.063 0.069 0.068 0.033 Scratch 300 300 300 300 300 300 resistance
(g) Black good good good good good good visibility
TABLE-US-00004 TABLE 4 Details of the antireflection films of
Comparative Examples and experimental results thereof Comparative
Comparative Comparative Comparative Example 1 Example 2 Example 3
Example 4 AG coating Comparative Comparative Comparative
Comparative solution Preparation Preparation Preparation
Preparation Example 1 Example 2 Example 3 Example 4 AG dry 6 6 6 6
thickness(.mu.m) LR coating Preparation Preparation Preparation
Preparation solution Example 6 Example 6 Example 6 Example 6 Total
Haze (%) 2.1 3.2 0.6 5.4 Internal 1.7 2.5 0.4 5.3 Haze (%)
Rz(.mu.m) 0.3469 0.639 0.1546 0.1306 Average 1.1 1.1 1.1 1.1
reflectivity (%) Gloss (20.degree./60.degree.) 24/54 23.5/49
28/53.36 28.5/55.5 Image clarity 59.3 56 80 68.3 0.125 mm slit
Image clarity 60.6 57.1 81 72 0.25 mm slit Specular 84.08 79.76
87.2 76.5 reflection light intensity Hiding power 0.112 0.612 0.004
0.003 Black visibility moderate poor good poor Scratch 300 300 300
300 resistance (g)
As shown in Table 1 and 2 above, the hard coating layers of the
antireflection films of Examples satisfy the condition that a
ten-point average roughness (Rz) of the surface irregularities is
0.05 .mu.m to 0.2 .mu.m and an internal haze is 0.5% to 5%, and
accordingly, it was confirmed that the sparkling phenomenon can be
prevented, and that optical characteristics such as enhanced
visibility, excellent external black visibility and contrast ratio,
etc. can be secured. Further, in the result of the diffuse
distribution of the reflected light source for the antireflection
films of Examples, the average value of the ratio of the respective
light intensity values to the specular reflection light intensity
values at an angle of .+-.1.degree. and -1.degree. from the
specular reflection was maintained in the range of 0.005 to 0.100,
thereby confirming that it is possible to implement improved
antireflection effect and hiding power of panel defects.
In contrast, the ten-point average roughness of the surface
irregularities of the hard coating layers of the antireflection
films of Comparative Examples 1 and 2 exceeded 0.2 .mu.m, and
accordingly, not only the image clarity and gloss were relatively
low, but also the deterioration of resolution, such as sparkling,
appeared. Moreover, the value of the hiding power of panel defects
exceeded 0.100, thereby indicating that the image appeared to be
distorted and the clarity of colors including black color was
lowered.
In addition, the internal haze of the hard coating layers of the
antireflection films of Comparative Examples 3 and 4 was less than
0.5%, and the image clarity and gloss could be secured to some
extent, but the average value of the ratio of the respective light
intensity values to the specular reflection light intensity values
at an angle of +1.degree. and -1.degree. from the specular
reflection was considerably low, thereby indicating that that it
was difficult to secure sufficient hiding power of panel
defects.
* * * * *